Field
This disclosure relates to a composite anode active material, an anode and a lithium battery each including the composite anode active material, and a method of preparing the composite anode active material.
Description of the Related Technology
Lithium batteries have high voltage and high energy density, and thus are used in various applications. Devices such as electric vehicles (e.g., HEVs or PHEVs) should be operable at high temperatures, be able to charge or discharge a large amount of electricity, and be used on a long term basis, and thus require lithium batteries having high-discharge capacity and enhanced lifespan characteristics.
Carbonaceous materials are porous and stable with little volumetric change during charging and discharging. Meanwhile, carbonaceous materials may lead to a low-battery capacity due to the porous structure of carbon. For example, graphite, which is an ultra-high crystalline material, has a theoretical capacity density of about 372 mAh/g in the composition of LiC6. Also, carbonaceous materials have poor high-rate characteristics.
A metal alloyable with lithium may be used as an anode active material having a high electric capacity compared to the carbonaceous material. Examples of the metal alloyable with lithium include silicon (Si), tin (Sn), and aluminum (Al). However, although the metal alloyable with lithium has a high-discharge capacity, volumetric change of the metal is large during charging and discharging, and thus the metal alloyable with lithium may easily deteriorate. Accordingly, a battery including the metal alloyable with lithium may have relatively poor life-time characteristics.
In order to reduce volumetric change of the metal alloyable with lithium, a composite may be formed by dispersing a metal alloyable with lithium in a matrix of a metal oxide or an alloy having electrochemically low reactivity or inertness. However, even when the metal alloy with lithium is dispersed in the matrix, volumetric change of the composite due to the volumetric change of the metal alloyable with lithium is not preventable, and thus resulting in deterioration of the composite and a decrease in lifespan characteristics of the battery may occur.
Therefore, lithium batteries with improved discharge capacity and lifespan characteristics are still needed.